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The Special Senses Eye and Ear. Lecture 10. The special senses of the eyes and ears are SENSORY input devices. The eyes and ears detect sensory information from the environment. They are responsible for sending this input to the brain for interpretation.

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The Special Senses Eye and Ear

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The Special Senses Eye and Ear

Lecture 10

  • The special senses of the eyes and ears are SENSORY input devices. The eyes and ears detect sensory information from the environment. They are responsible for sending this input to the brain for interpretation.

  • The special senses DO NOT interpret the stimuli.

Some definitions


- change in the environment


- device to detect a stimulus


- the interpretation of the stimulus causing some action from the body


  • Sclera = outer protective layer of the eye white portion.

  • Cornea = transparent anterior part of the sclera,.

  • Choroid = middle layer of the eye.

  • Iris = muscular structure that give the eye its color, allows light to pass through.

  • Pupil = opening in the center of the iris.

  • Lens = behind the pupil, focus and bend light.

  • Retina = innermost layer, contains the vision receptors.

The eye


  • Aqueous fluid = watery liquid found in the anterior cavity of the eye.

  • Vitreous fluid = jelly like fluid found behind the lens in the posterior cavity of the eye.

  • Lacrimal glands & ducts = produce and drain tears.

  • Optic nerve = carries visual impulses from the retina to the brain.

  • Conjunctiva = mucous membrane lining the eyelids and anterior portion of the sclera.

Section through the eye

The Eye





Dacry/o lacrim/otear, tear duct.


Irid/o iri/oiris


Cur/o core/o pupill/opupil

Ophthalm/o ocul/oeye






Ton/otension, pressure.

New Suffixes

-spasm twitching

e.g., blepharospasm

-opia vision

e.g., diplopia

-plegia paralysis

e.g., iridoplegia

- Bi- bin- two.

-ician one who.

-phobia abnormal fear of or aversion to

An OPHTHALMOSCOPE is a device to

examine the interior of the eye

High Blood Pressure (HTN) may cause OPHTHALMODYNIA (pain in the eye)

A swelling of the eyelid is called


Plastic surgery of the eye to remove wrinkles is called an eye tuck or


  • Dirty contact lenses can cause a severe infection called KERATITIS.

  • Rupture of the cornea is known as KERATORRHEXIS. The cornea is incised with an instrument known as a KERATOTOME.

  • A laser KERATOTOMY is a procedure that can eliminate the need for eyeglasses.

  • MYOPIA (nearsightedness) is a condition where the stimulus image falls in front of the retina.

  • The opposite of myopia is farsightedness or HYPEROPIA where the image falls behind the retina.

  • Both myopia and hyperopia can be corrected with glasses.

  • The eyelids protect the eyes, shade eyes during sleep, and spread lubricating fluid.

  • This lubricating fluid come from three areas: LACRIMAL GLANDS located above the outer corner of each eye, LACRIMAL DUCTS which drain gland secretions into the lacrimal sacs.

  • The term DACRY/O is used to denote tears.

  • The word DACRYADENALGIA means

    pain in a tear gland

Disease & Disorder Terms

  • Blepharitis = inflammation of the eyelid.

  • Blepharoptosis = drooping of the eyelid.

  • Conjunctivitis = inflammation of the conjunctiva.

  • Dacryocystitis = inflammation of the tear sac.

  • Diplopia = double vision.

  • Iridoplegia = paralysis of the iris.

  • Keratitis = inflammation of the cornea.

  • Ophthalmalgia = pain in the eye.

  • Ophthalmorrhagia = rabid flow of blood from the eye.

Disease & Disorder Terms

  • Photophobia = fear of, sensitivity to light.

  • Retinoblastoma = tumor arising from the developing retinal cell.

  • Sclerokeratitis = inflammation of the sclera and cornea.

  • Scleromalcia = softening of the sclera.

  • Astigmatism = defective curvature of the refractive surface of the eye.

  • Cataract = clouding of the lens of the eye.

  • Glaucoma = increased intraocular tension.

Disease & Disorder Terms

  • Hyperopia = farsightedness.

  • Myopia = nearsightedness.

  • Nyctalopia = poor vision at night.

  • Nystagmus = involuntary, rhythmic movements of the eye.

  • Retinitis pigmentosa = hereditary progressive disease marked by night blindness with atrophy and retinal pigment changes.

  • Strabismus = squint or crossed eyes.

  • Sty = an acute infection of the secretory glands of the eyelids.

Surgical Terms

  • Blepharoplasty = surgical repair of the eyelid.

  • Dacryocystotomy = incision into the tear sac.

  • Iridectomy = excision of part of the iris.

  • Keratoplasty = surgical repair of the cornea.

  • Cryoextraction of the lens = cataract is lifted from the eye with an extremely cold probe.

  • Enucleation = removal of the eye.

  • Vitrectomy = removal of all or part of the vitreous fluid.

Surgical Terms

  • Redial keratotomy = spoke like incisions are made to flatten the cornea, correctingn nearsightedness (myopia).

  • Strabotomy = incision into the tendon of an extrinsic muscle to relieve strabismus.

  • Fluorescein Angiography = x-ray filming of the blood vessels using fluorescing dye.

  • Keratometer = used to measure the curvature of the cornea.

  • Ophthalmoscope = used for visual examination of the eye.

Procedural Terms for the EYE

  • Optometer = used to measure vision, power and range.

  • Pupillometer = used to measure width and diameter of the pupil.

  • Tonometer = used to measure pressure within the eye, used to diagnose glaucoma.

Complementary Terms

  • Binocular = pertaining to both eyes.

  • Intraocular = pertaining to within the eye.

  • Lacrimal = pertaining to tears or tear duct.

  • Ophthalmic = pertaining to the eye.

  • Ophthalmologist = physician who specializes in ophthalmology.

  • Optic = pertaining to vision.

  • Optician = one who is skilled in filling prescription for lenses.

  • Retinopathy = noninflammatory disease of the retina.

Complementary Terms

  • Miotic = agent that constricts the pupil.

  • Mydriatic = agent that dilates the pupil.

  • Oculus dexter = OD, right eye.

  • Oculus sinister = OS, left eye.

  • Oculus uterque = OU, each eye.

  • Optometrist = health professional who prescribes corrective lenses.

  • Visual acuity = VA, sharpness of vision of either distance or nearness.

The Ear

  • The ear has three divisions:

    outer ear (external ear)

    middle ear

    inner ear

  • The outer ear takes sound waves and directs them into the ear canal.

  • The middle ear takes those sound waves and converts them to electrical energy.

  • The inner ear takes that electrical energy and transmits it to the brain. It also is responsible for balance.

  • The external ear contains the AURICLE. This structure is the earlobe (PINNA) that directs sound into the auditory canal. At the end of the auditory canal, you find a thin membranous sheet called the TYMPANIC MEMBRANE (eardrum).

  • Vibrations of the eardrum cause a mechanical vibration of the three middle ear bones. The MALLEUS (hammer), INCUS, and STAPES. Each of these bones are connected. The malleus is connected to the tympanic membrane.

  • Once the vibration is detected at the last bone (STAPES), the stapes cause a vibration at the opening of the inner ear, OVAL WINDOW.

  • The middle ear is connected to the throat by the EUSTACIAN TUBE.

  • The inner ear includes the COCHLEA and SEMICIRCULAR CANALS.

  • The cochlea is filled with fluid and small hair cells that detect minute vibrations. These vibrations are interpreted by the brain via the AUDITORY NERVE.

  • The SEMICIRCULAR CANALS are also filled with fluid. Sudden movements of the head cause this fluid to move. This eventually causes dizziness (vertigo).


  • Auricle, pinna = bilateral of the head, directs sound waves in the external auditory meatus.

  • External auditory meatus = short tube ends at the tympanic membrane.

  • Tympanic membrane = eardrum semitransparent membrane that separates the external meatus and the middle ear cavity.

  • Eustachian tube = connects the middle ear and the pharynx (throat). Regulates air pressure.

  • Ossicles = bones of the middle ear, carry sound vibrations, malleus (hammer), incus (anvil), stapes (stirrup).


  • Inner ear Labyrinth = bony spaces within the temporal bone of the skull.

  • Cochlea =snail shaped and contains the organ of hearing.

  • Semicircular canals & vestibule = contains receptors and endolymph that help the body maintain its balance or equilibrium.

  • Mastoid bone and cells = located in the skull bone behind the external auditory meatus.

Combining Forms for the EAR

  • Acou/o audi/o = hearing

  • Aur/i aur/o = ear.

  • Labyrinth/o = labyrinth.

  • Mastoid/o = mastoid bone.

  • Myring/o = tympanic membrane (eardrum).

  • Ot/o = ear.

  • Staped/o = stapes (middle ear bone).

  • Tympan/o = tympanic membrane, eardrum.

  • Salping/o eustachian tube

Disease and Disorder Terms

  • Labyrinthitis = inflammation of the labyrinth.

  • Mastoiditis = inflammation of the mastoid bone.

  • Myringitis = inflammation of the eardrum.

  • Otalgia = pain in the ear.

  • Otomycosis = fungus in the ear.

  • Otopyorrhea = discharge of pus from the ear.

  • Tympanitis = inflammation of the middle ear.

  • Otitis Meida.

  • Ceruminoma = tumor of the glands that secrete earwax.

Disease and Disorder Terms

  • Otitis externa = inflammation of the outer ear.

  • Otitis media = inflammation of the middle ear.

  • Tinnitus = ringing in the ears.

  • Vertigo= dizziness.

Surgical Terms

  • Labyrinthectomy = excision of the labyrinth.

  • Mastoidectomy = excision of the mastoid bone.

  • Myringoplasty = surgical repair of the tympanic membrane.

  • Myringotomy = incision of the tympanic membrane, performed to release pus and relieve pressure in the middle ear.

  • Tympanoplasty = surgical repair of the eardrum.

Procedural Terms

  • Acoumeter = instrument used to measure, acuteness of hearing.

  • Audiogram = graphic record of hearing.

  • Audiometry = measurement of hearing.

  • Otoscopy = visual examination of the ear.

  • Tympanometer = instrument to measure middle ear functions.

Complementary Terms

  • Audiologist = one who is skilled in and specializes in audiology.

  • Audiology = study of hearing.

  • Otologist = physician who studies and treats diseases of the ear.

  • Otology = study of the ear.

  • Otorhinolaryngologist = ENT physician who studies and treats diseases and disorders of the ear, (ear, nose, & throat).

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